Certain types of problems are difficult for computing systems to solve. For example, image and video labeling is important for computers to understand images and videos and for image and video search. But automatically labeling images and videos is a hard problem for computers to solve on their own. Yet such is a fairly simple task for humans based on “common sense”, although such manual labeling may be tedious and costly. Thus there may be advantages to combining humans and computers to solve certain “common sense” problems that would otherwise be very difficult for computers alone and very costly for humans alone.